Maintenance – Skyd Control

https://youtu.be/hzHzlW6JLMI I’ve owned a plethora of motorcycles, ATVs, and dirt bikes through the years and regularly flushing your brake fluid is important on any of these machines in order to maintain a properly working brake system. Stopping is pretty important, you should make sure your machine stops before you make it go. But Chinese manufactured bikes (like my newly purchased RPS Hawk 250) and ATVs come with fluid from the manufacturer that’s questionable at best. Why should you do a brake fluid flush on a Chinese Dirt Bike or ATV? One major advantage to buying Chinese manufactured powersports is the cost. They’re keeping these costs low through a number of avenues and fluids is a probable spot for them to save money. It’s best practice to flush the factory fluid and put in a quality brake fluid so you know what’s in there. Annual flushing is also recommended for any motorcycle or ATV, Chinese or otherwise. Let’s dive in a little bit further as to why the quality of your brake fluid matters. Water, Air, and Corrosion - OH MY! Your hydraulic brake system works by using hydraulic pressure (imagine that). It basically works like this: Brake lever is applied activating the master cylinder pistonThe piston pushes brake fluid through the brake lineThe increase in pressure forces the caliper piston outThis in turn pushes the brake pads towards the brake rotor where friction takes over This system works perfectly well when kept in good condition. But if you introduce something into the system that doesn’t belong, it becomes an issue, one that could prove dangerous. Air Having air in your brake lines causes a spongy feeling in the lever. This is because the air is much more compressible than brake fluid. So when pressure is applied to the system, the pockets of air will compress allowing for more movement of the brake lever and increased “squishiness” (that’s the technical term btw, look it up). Water Water is not compressible like air but poses another threat all together. Interestingly a property of most brake fluids is that it attracts water (more on that later). Water causes corrosion which as you can imagine is not a good quality in a brake system. In addition, water has a lower boiling point making your system more susceptible to heat. Corrosion That corrosion that’s forming in your brake system from other contaminants like water is going to wreak havoc. The small bits of corrosion, usually in the form of rust, can interfere with safe operation of the pistons that engage the system either preventing them from engaging or from disengaging. Both are bad. What Makes Good Fluid go Bad (hint: it’s not peer pressure) Let’s assume you’re starting out with all brand new unmolested parts in your brake system and some good quality brake fluid. That means you’re good forever right...there’s no contaminants in there. WRONG! Brake fluid (3 out of the 4 types) is Hygroscopic. Hygroscopic: adjective - readily taking up and retaining moistureMerriam Webster Because brake fluid has this property, it absorbs water molecules from the environment through seams and microscopic pores in the system. It’s just the nature of the beast. Once the water is in there, as we’ve touched on already, it starts to corrode the system and lower the boiling point of your fluid. The longer your fluid goes unchanged, the more water, and consequently the more corrosion becomes present. I hope you’re starting to see why this is an important subject. Old contaminated brake fluid will usually be darker in color and easily distinguishable from fresh fluid, that alone is indicator enough that there’s some stuff in there you need to get out. DOT what now? Likely you’ve seen various DOT ratings on brake fluid bottles. Maybe you’re not sure which one you need, or you don’t know the difference between them. Allow me to shed a little light. What’s in the brake fluid DOT 3, DOT4, and DOT 5.1 are all Glycol-Ether based while DOT 5 is Silicone based. Glycol and silicone based fluids are NOT compatible so don’t mix them. In fact, unless your system specifically calls for DOT 5, I’d just steer clear of it. It has its place, but typically motorcycles and ATVs are not using it. I have read that Harley Davidson used DOT 5 from the factory on some bikes but I’ve not confirmed that. DOT 5.1 is the preferred fluid for ABS brake systems so if you have a motorcycle with ABS there’s a chance that this is what you should be using. When in doubt, check your manual or your master cylinder cap for the manufacturer’s recommended brake fluid. Brake fluid also has additives in it so that it doesn’t react with your brake system parts and cause corrosion (like the water). These additives and especially Glycol based fluids tend not to react well with paint so be careful not to spill brake fluid on any painted surfaces. It’s Getting Hot in Here Brake systems get hot so it’s important that brake fluid be able to take the heat or get out of the kitchen….er, master cylinder I guess. Have a look at this table which lays out the boiling point of each type of brake fluid. Wet boiling point is defined as having 3.7% water content (take note of how much it lowers the boiling point). Keep in mind, the older the fluid, the more water it will have absorbed. Brake FluidDry Boiling PointWet Boiling PointDOT 3401 degrees Farenheit284 degrees FarenheitDOT 4446 degrees Farenheit311 degrees FarenheitDOT 5 500 degrees Farenheit356 degrees FarenheitDOT 5.1500 degrees Farenheit356 degrees Farenheit If the fluid reaches its boiling point it will start to vaporize in your lines and this vapor is much more compressible than the fluid. This will cause brake fade making the brakes feel spongy and requiring the levers be depressed further for the brake pads to contact the discs. So which one do you use? The type of brake fluid your motorcycle or ATV uses will be stamped on the master cylinder cover. These days that’s usually DOT 4 or DOT 5.1. Older machines may say DOT 3. All 3 of these are compatible and will mix fine so don't’ sweat that part too much it’s ok to flush one with another. However, the caveat is this. If your ride calls for DOT 4, don’t put DOT 3 in it, that’s just asinine. You’re using lower performing fluid for no real reason. On the contrary going from DOT 3 to DOT 4 is said to be fine, in fact it’s probably wise so feel free to give your brake system a small upgrade. Mixing brands is typically accepted as well. If you have any doubts, just use whatever grade is stamped on your master cylinder or in your manual. DOT 5.1 is a fickle beast. Sure you get a higher boiling point but that’s at the cost of it absorbing water more quickly. If your system calls for, use it. Typically you’ll find this is true of motorcycles with ABS. If it doesn’t call for it, I’d probably stick to DOT 4. If you still want to switch to 5.1 you can, but you should flush the fluid more often. The magical word “Synthetic” This is a bit of a misnomer in the brake fluid world. Technically speaking ALL brake fluid is synthetic, it contains no petroleum products. DOT 5 is silicon based and sometimes referred to as the only “synthetic” brake fluid. Let’s toss DOT 5 out the window for a minute...it’s confusing and for 95% of riders they don’t even need to know about it. Plus it’s pricey. Let’s get back to the other 3 kinds of brake fluid. The inclusion or exclusion of the word synthetic on the bottle is simply a marketing choice it seems. Glycol based fluids may or may not contain this word on the bottle. Just stick to your flavor of DOT and all will be as it should be. A Special Word about Chinese Machines I think that the Chinese manufacturers have come a long way in the last decade or so with all of their powersports machines. I have an RPS Hawk 250 myself that I picked up new and I’m quite impressed with the build quality for the price. They do require a little bit more TLC up front and regular maintenance is a must. Let me make a suggestion here about the brake fluid. My bike for example says it takes DOT 4 fluid. Is that what they put in it? Perhaps, but even if they used the proper grade I’d question how old it is, how much moisture it has absorbed, and it’s quality to begin with. Chances are the bike sat in a container crossing the ocean for quite some time as well. CHANGE THE DARN FLUID! It’s silly not to, it’s so cheap and easy to do, why chance it. Put something in there that you know is of good quality and is fresh….like Nike says - JUST DO IT! So now you know WHY to change your brake fluid and which kind to use….but how the hell do you flush the brakes anyway? If you don’t know how, you should learn. It’s not difficult, nor is it expensive, and it sure beats taking your ride to the powersports shop every year or two and paying labor costs. How to Change the Brake Fluid in your Motorcycle, Dirt Bike, or ATV If you’ve got 12 minutes to spare and are ok listening to me blabber on then check out the video at the top of this page where I flush the front and rear fluid on my brand new RPS Hawk 250 Dirt Bike. However, if you’d like to read about it instead I’ll walk you through the basic process below. Tools & Supplies needed: Proper type of Brake Fluid (DOT 4 in my case)Screwdriver (Recommend JIS type)8mm Combo Wrench (or whatever size your bleed screw is)3’ length of 1/4” or 3/16” ID Vinyl tubingCatch containerRags and/or Paper towelsGloves Step 1: Once you’ve gathered your tools and supplies you’re ready to get started. I always open my master cylinder first. Typically your front will have a cover on it held on by 2 phillips style screws. On Japanese and Chinese bikes like mine, a JIS screwdriver is preferable here. Remove your cover and set it someplace safe. This allows you to keep an eye on your fluid level while you’re flushing the system. Step 2: Next you’ll want your box end wrench to open and close your bleeder screw. I like to put the wrench on the bleeder first, and then attach my piece of vinyl hose after. This will allow you to open and close the bleeder without disturbing your tube full of brake fluid. Step 3: Now you’re ready to start displacing the old fluid. Pump up your brake lever (front or rear depending on which one you’re working on) until it feels firm, and hold it there. Step 4: Open the bleed screw and fluid should start making its way through your tube and towards your catch can. You'll start feeling the pedal or lever going down. Step 5: Once the brake lever has depressed all the way, close your bleeder BEFORE letting go of the lever so as not to draw air into the system. Once the bleeder screw is closed up you can let go of your lever. Step 6: Repeat steps 3-5 again, stopping periodically to check the fluid level in your master cylinder reservoir. You don't want it to get so low that it draws air into the system or else you’ll be spending extra time trying to bleed out the air. Add new fluid as needed until you’re satisfied that you’ve bled out all the old fluid. Step 7: Top off your fluid one last time and replace the master cylinder cover. Make sure your bleed screw is snug, and clean up. If you did things right, you should have no air in your lines and they’re now full of fresh fluid. Job well done, grab a beer or other beverage of your choice and revel in your glory. If you’re replacing old brake fluid it will be relatively easy to tell once you’ve completely flushed it, especially if you use clear vinyl tubing like I did. Old fluid is discolored, usually some shade of brown. New fluid is light amber colored so you’ll see it change as you bleed the system. If however, like me you’re evacuating whatever Chinese fluid they’re passing off as “brake fluid” out of the system...well it’s a bit trickier. You could disassemble the system and run it dry then start new, but I took the easier route. Perhaps slightly less effective at getting ALL the old stuff out but I’m confident I got very close. I ran way more new fluid into the lines than it could hold that way I was sure I had pushed out all the old questionable fluid. That’s about all there is too it folks. Once you have your bike back together you want to be sure and test out those brakes before riding. Keep the rubber side down!